1. Field of the Invention
The present invention relates to cellular networks and more particularly to management of radio frequency (RF) calls in a mobile telephone system.
2. Description of Related Art
In mobile telecommunication systems, an RF performance of the system is typically managed by responding to unacceptable signal characteristics and independently varying one of the RF management mechanisms. For instance, a system may respond to a poor carrier signal strength-to-interference (C/I) ratio of a call by increasing power. While, this power boost may strengthen the signal of the call being monitored, it may also have a corresponding negative affect on another call by increasing the interference in response to the higher noise levels caused by the higher power level. Another conventional RF management technique may be to switch a call from one channel frequency, with relatively high interference, to another channel with relatively low interference. Current RF management functions, however, are designed to operate independently and asynchronously. As a consequence, these RF management functions sometimes operate at cross-purposes, i.e., improving the signal of one mobile while increasing the interference experienced by other mobiles.
In addition, currently available RF management algorithms are essentially fixed in their behaviors, wherein decisions are based on configuration information and/or averaged measurements. As a result, RF management functions tend to have a large number of parameters which must be continually updated to maintain an optimum performance in the cellular network or telecommunication system. RF management algorithms are also typically associated with a variable parameter such as power level, call mode, and channel assignment. That is, one algorithm is used for power management while another manages channel allocation, and the like. RF management algorithms may also be coordinated to avoid significant interference in their respective operations. For example, handoff requests can be delayed until after power control actions have taken place, thus allowing time for the RF signal strength readings to settle. However, channel allocation, handoff and power control decisions are typically conducted in different places in a cellular network or telecommunications system, rather than at a centralized location, which makes coordinating activities difficult.
The effort to maintain and optimize RF management parameters in a cellular network can be reduced through the use of off-board management systems and expert systems. By analyzing past performance information received from a cellular system and comparing that information against a given set of rules, an expert system can determine when the system is getting "out of tune" and then recommend changes to the various parameters to correct the condition. In some cases, the expert system may also be able to make the changes itself. However, these expert systems utilize past average measured criteria and thus cannot make real-time decisions for specific mobile units to implement an appropriate dynamic corrective action. In addition, expert systems are highly complex, having an ability to crunch all the numbers and performance measurements to optimize performance. Such a system however requires undesired complexity. A more simpler solution is desired for handling RF channel allocation on a cellular network.
The problem in the art is further characterized in that management of the RF channels, particularly in terms of handoff, has become a very complicated and cumbersome process. The means used to decide whether or not a mobile should be assigned to a given channel or moved to a different channel has become a very complicated, large engineering problem. A lot of parameters are associated with the cell sites, in particular, to determine when particular mobiles need to be handoff and help decide where the mobiles need to go. It thus becomes difficult for operators of large networks to manage their system, and optimize behavior properly. This means that the quality over time begins to suffer. The operators are unable to keep up with the complexities of the system over time.
A need exists for a centralized RF management system that operates substantially synchronously across all variables for providing improved management of RF channels in a cellular network.